Environmental regulations are restricting the use of thread compound products containing substantial amounts of metallic additives such as copper, lead, nickel, zinc, antimony or their salts for many applications. However, generally, thread compounds require these metallic agents to provide galling resistance and frictional properties to the thread compound products for optimum performance. As a result of the environmental restrictions and the removal or reduction in amount of these metallic agents, premature connection wear and failures are more prevalent due to the use of unrestricted agents in place of the metallic agents that have inferior galling resistance and frictional properties.
Oilfield thread forms require products with high film strength and specific coefficient of frictional properties. Because thread faces are often subjected to bearing stresses in excess of 50,000 psi, additional downhole connection engagement can result in bearing stresses capable of rupturing the protective "anti-seize" film. This additional engagement can result in wear, galling or complete connection failure.
Conventional anti-seize compounds work by placing a dissimilar metal or metallic containing film between two like substrates. The dissimilar metallic film provides a barrier between the two like substrates to protect against direct contact of the substrates which, under the pressure and heat of use, could result in fusing the substrates together. The fusion could then ultimately result in galling upon disengagement of the connection or in the worst case scenario, cause catastrophic failure of the connection.
In addition to restricting the use of metallic additives, many of the environmental regulations are restricting the use (or the potential introduction into the environment) of various organic fluid additives. These additives chemically react with the substrate to form softer compounds on the surface, which reduce the potential for galling. The organic fluid additives facing regulation include those containing antimony, barium, chlorine, lead, phosphorus, and/or zinc.
Products containing lower quantities of metallic and/or organic fluid additives have been formulated to perform in certain applications. Commercial products free of these additives, however, still lack the galling resistance and frictional properties required to perform optimally in severe applications.
U.S. Pat. No. 5,093,015 discloses an anti-seize composition including a suspending agent, a resin bonding system, a thinning agent, and a metallic flake. The anti-seize properties of this composition resulted from the bonding of the metallic flake to the threaded connection to interpose a dissimilar metal between threaded connection surfaces. Although this composition reduces metal loss into the environment, this composition still relies on a metallic agent to supply the anti-seize protection.
Thus, there is a need for an environmentally responsible lubricant that provides adequate anti-seize and frictional properties including the reduction of the additional downhole engagement of threaded connections used in oilfield drilling operations such as tool joints and drill collars. Specifically, there is a need for an environmentally responsible lubricant that does not contain heavy metals or potentially toxic organic fluid additives which can potentially end up in the drilling effluent or require hazardous waste classification.